This invention relates to weld guns and more particularly to weld guns especially suitable for use in industrial automotive applications.
Weld guns are in common usage in many industrial applications and in particular in automotive applications. Whereas a myriad of weld gun designs have been proposed and/or utilized commercially, there is still a need for a simpler weld gun design, providing a less expensive cost of assembly; for a weld gun design that is easier to service, thereby reducing servicing costs; and for a weld gun design that provides a longer life, thereby reducing replacement costs.
This invention is directed to the provision of an improved weld gun.
More specifically, this invention is directed to the provision of a weld gun design that is simple, inexpensive and durable.
The weld gun of the invention is of the type including a frame structure, a weld arm, and a pivot structure pivotally mounting the weld arm on the frame structure.
According to a feature of the invention, the pivot structure comprises a pivot pin carried by the frame structure, an inner race mounted on the pivot pin, an annular member of electrically insulative material positioned in an aperture in the weld arm, an outer race mounted within the annular member, and a ball race rollably positioned between the inner race and the outer race. This arrangement allows the provision of a relatively robust ball bearing at the pivot structure at a relatively low cost.
According to a further feature of the invention, the weld arm comprises a first weld arm; the inner race comprises a first inner race; the annular member comprises a first annular member; the outer race comprises a first outer race; the ball race comprises a first ball race; and the weld gun further includes a second weld arm, a second inner race mounted on the pivot pin, a second annular member of electrically insulative material positioned in an aperture in the second weld arm, a second outer race mounted within the second annular member, and a second ball race rollably positioned between the second inner race and the second outer race. This arrangement allows the provision of a relatively inexpensive and yet robust ball bearing pivot structure for both arms of a pinch type weld gun.
According to a further feature of the invention, the first weld arm includes laterally spaced first and second arm portions; the second arm is positioned between the spaced arm portions of the first weld arm; the first inner race, first annular member, first outer race, and first ball race journal the first arm portion of the first weld arm on the pivot pin; and the weld gun further includes a third inner race mounted on the pivot pin, a third annular member of electrically insulated material positioned in an aperture in the second arm portion of the first arm, a third outer race mounted within the third annular member, and a third ball race positioned between the third outer race and the third inner race. This arrangement allows the provision of a robust, inexpensive ball bearing interconnection between both arms of a bifurcated weld arm and a further weld arm positioned between the spaced arm positions of the first weld arm.
The weld gun of the invention is also of the type including a frame structure, a transformer carried by the frame structure and including a coolant passage system, a weld arm mounted on the frame structure and including a weld tip at one end of the arm, and a shunt fixedly secured at one end thereof to another end of the weld arm and fixedly secured at another end thereof to the transformer.
According to a further feature of the invention, the other end of the shunt includes a coolant passage communicating with the transformer coolant passage system. With this arrangement a coolant may be delivered to the transformer coolant passage system through the coolant passage at the other end of the shunt.
According to a further feature of the invention, the weld arm comprises a first weld arm; the shunt comprises a first shunt; and the weld gun further includes a second weld arm mounted on the frame structure and including a weld tip at one end of the arm and a second shunt fixedly secured at one end thereof to another end of the second weld arm and fixedly secured at another end thereof to the transformer proximate the other end of the first shunt; and the other end of the second shunt includes a coolant passage communicating with the transformer coolant passage system. With this arrangement the coolant may be delivered to the transformer coolant passage system through the coolant passage in the other end of the first shunt and discharged from the transformer coolant passage system to a further coolant passage in the other end of the second shunt, whereby to provide a continuous flow of coolant through the transformer coolant passage system.
The weld gun of the invention is also of the type including a frame structure, a weld arm mounted on the frame structure, an electrode mounted at one end thereof on the weld arm and defining concentric cooling passages for delivery of a cooling liquid from the one electrode end to a weld tip at an opposite end of the electrode and return movement of cooling liquid from the weld tip to the one electrode end, a source of cooling liquid, and coolant flow means interconnecting the one end of the electrode and the cooling liquid source and operative to deliver cooling liquid from the source to the one electrode end for delivery to the weld tip and receive cooling liquid from the one electrode end for return to the source.
According to a further feature of the invention, the coolant flow means comprises a distribution device mounted on the frame structure as a location remote from the one end of the electrode, tubing structure for delivering coolant liquid from the source to the distribution device and returning coolant liquid from the distribution device to the source, and concentric tubing extending from the distribution device to the one end of the electrode for respective connection to the respective cooling passages defined by the electrode. This arrangement minimizes the shear volume of the tubing required to deliver cooling liquid to the electrode and return cooling liquid to the source, thereby simplifying the weld gun both from a constructional and an operational standpoint.
According to a further feature of the invention, the electrode comprises a first electrode and the weld arm comprises a first weld arm; the weld gun further includes a second weld arm mounted on the frame structure and a second electrode mounted at one end thereof on the second weld arm and defining concentric cooling passages for delivery of cooling liquid to a second weld tip on the opposite end of the second electrode and return movement of cooling liquid from the second weld tip to the one end of the second electrode; and the coolant flow means further includes further concentric tubing extending from the distributor device to the one end of the second electrode for respective connection to the respective cooling passages defined by the second electrode. This arrangement further reduces the shear volume of the tubing required to deliver and return the cooling liquid.
According to a further feature of the invention, the weld gun includes a transformer; the frame structure defines a cage structure mounting the transformer; and the distributor device comprises a distributor block mounted on the cage structure proximate the transformer. This arrangement provides a convenient packaging assembly that specifically removes tubing from the operational aspects of the weld gun.
According to a further feature of the invention the weld gun includes a shunt connected at a first end thereof to the one end of the electrode and at a second end thereof to the transformer, and the first end of the shunt clampingingly engages the one end of the electrode in surrounding relation to the concentric cooling passages defined by the first electrode. This specific arrangement further minimizes the tubing in the vicinity of the operational aspects of the weld gun.